Fixation elements (e.g., pegs, screws, pins) are well known in the field of bone fixation and consist completely or partly of thermoplastic materials which can be softened or melted completely or preferably at their surface by application of electromagnetic radiation (e.g. laser light) thereto. Softening or melting of the thermoplastic material permits the fixation elements to adapt their shape to a surrounding cavity (e.g. a plate hole or a bore in a bone) to achieve a better anchorage therewithin. In some cases, the softened or melted thermoplastic material can penetrate into cavities and slits of surrounding bone material so that a particularly efficient anchorage takes place.
However, present fixation elements prevent a determination of an optimal amount of energy needed to properly anchor the fixation element in the bone, instead relying only on rough estimates based on various parameters (e.g., thermoplastic material, volume of the fixation element, absorptive properties of the thermoplastic material or possibly contained chromophores therein, and power of the light source). The subjective estimation can lead to an irradiation duration that is either too short or too long, thus reducing an efficacy of a fixation element anchoring procedure. Specifically, if the irradiation period is too short, the fixation element undergoes an insufficient softening and is unable to adapt to a shape of a bone or other environment in which it is implanted, thus causing a poor anchorage. If the irradiation period is too long, an excessive liquefaction of the fixation element results, permanently damaging the mechanical stability of the fixation element. Furthermore, depending upon the supplied excessive quantity of energy, over-irradiation can also lead to an overheating of the thermoplastic material to further reduce an anchoring strength of the fixation element in the bone.